In FIG. 1, an opposed-piston, opposed-cylinder (OPOC) engine 10 is shown isometrically. An intake piston 12 and an exhaust piston 14 reciprocate within each of first and second cylinders (cylinders not shown to facilitate viewing pistons). Exhaust pistons 14 couple with a journal (not visible) of crankshaft 20 via pushrods 16. Intake pistons 12 couple with two journals (not visible) of crankshaft 20 via pullrods 18, with each intake piston 12 having two pullrods 18. The first and second cylinders in which the pistons reciprocate are parallel but offset from each other in the Y direction due to pullrods 18 associated with the cylinder shown front and leftward displaced in a negative Y direction with respect to pullrods 18 associated with the cylinder shown rear and rightward. Pushrods 16 are similarly situated with respect to each other. It is cost effective that all four pullrods 18 are identical in design and the two pushrods 16 are the same. However, a disadvantage of such an offset design is that the engine is wider than it would otherwise be if the two cylinders could be collinear. A torque is introduced due to the offset of the two cylinders.
One alternative to overcome the offset cylinders is a forked rod, such as is described in U.S. Pat. No. 1,322,824, invented by F. Royce. By employing a forked rod/blade rod configuration within the engine of FIG. 1, the length of the journal (or crank pin) can be reduced. Also, the cylinders are collinear. The width of the engine can be reduced and the unbalanced forces are reduced. However, a disadvantage of such a configuration is that the piston in one cylinder couples with the crankshaft by a forked rod and the corresponding piston in the opposing cylinder couples with the crankshaft by a blade rod thereby increasing part count for the engine. A system for coupling the rods to the crankshaft is desired which allows common parts to be used in the two cylinder, such as is possible with the configuration shown in FIG. 1, while allowing collinear cylinders, such as that shown U.S. Pat. No. 1,322,824.